Shaping devices are already known by means of which extruded articles, particularly hollow profiles or pipes, emerging from an extruder nozzle, are calibrated to desired outer and inner dimensions and are hardened at the desired outer dimensions or, in order to obtain the desired intrinsic rigidity, are cooled to the temperature provided for that purpose. Such shaping devices are known from the book by Walter Michaeli, Extrusions-werkzeuge fur Kunststoffe und Kautschuk", from Carl Hanser Verlag, Munich/Vienna, second fully revised and expanded edition, published 1991, particularly pages 321 to 329. Shown on page 323 is an external calibration with vacuum, in which the extrudate emerging from the extrusion tool is introduced in the form of a hollow profile at some distance after emergence from the nozzle lip of the extruder tool into a calibrating tool, by means of which the extrudate is passed through in the area of its surrounding outer surface, in contact with the mould surfaces of the calibrating tool. The contact without clearance of the surface of the extrudate on the individual mould surfaces of the calibrating tool is achieved by air passages, particularly slots located in the mould surfaces, and which are connected by supply lines to a vacuum source. In order to cool the extrudate, the calibrating tools are provided with one or more surrounding ducts for a heat treatment agent, and the vacuum can increase in the individual air passages or slots as the distance from the nozzle lip of the extruder tool increases. The temperature of the heat treating agent, in contrast to the mass temperature of the extruded profile, is extremely low and comes to about 20.degree. C. Connecting then to such so-called dry calibrators are usually one or more cooling baths, in which the sufficiently rigid profiles, with partial application of vacuum or wetting via spray nozzles or passage through water baths, are cooled to room temperature. In many cases sufficient surface quality of the extrudates produced cannot be achieved with such calibrating tools over a lengthy service life of the shaping device.
A further device for calibrating extruded profiles, particularly extruded hollow profiles of thermoplastics, has become known from DE 22 39 746 A, in which there is located at a spacing in the extrusion direction behind the extruder tool or injection head of the plastics worm extruder press, a vacuum calibrating device with a cooling device integrated therein. In connection with the vacuum calibration device there is provided a low-pressure calibration tank through which a coolant flows, the vacuum calibrating device being so designed that therein only the outer skin and any present outer profile portions such as fine contours of the profile to be calibrated are shaped into their final form. The residual heat still contained in the profile is removed by the coolant in the low pressure calibration tank. Located in the vacuum calibrating device are individual calibrating plates at a spacing from one another, which thus form cavities in the form of vacuum slots, through which the extruded article is suctioned with the aid of the applied vacuum against the mould surfaces of the individual calibrating plates. In the calibration device proposed here, in all cases of application perfect surface quality of the extruded article and a long service life of a device could not be achieved.